. >>> caterpillar reported first- quarter earnings. the revenue that fell short of the expectations. taking a live look at the big board, the dow is down 75. the nasdaq down 2. s&p down 4. >>> sales of previously-owned homes also dipped last month. the national association of realtors said sales fell 6% mostly because of a limited supply of available homes. but other signs point to sub stagetly more sales in the long- term. the average price did, 184,000. up 12% from march of last year. it's the largest year to year growth since 2005. >>> for the first time in eight years, the five most valuable companies in the world are all based in the united states. exxonmobil topped the list followed by apple, google, berkshire and walmart. last year, three chinese companies were in the top five and for the first time in three years, no company in the world is worth $400 billion. >>> gas prices continue to slip across the country and here in the bay area. analysts say they could be lower by the memorial holiday weekend. san francisco averages $4.0